Method of sizing nylon textile materials with coal acid compounds and resulting article



March 11, 1958 H. B. RICKERT ET AL METHOD OF SIZING NYLON TEXTILE MATERIALS WITH COAL ACID COMPOUNDS AND RESULTING ARTICLE Filed July 30, 1956 I 2 Pick up or Fin 119/? on Yarn .I'n

Percen age by 11/).

INVTORS. Herbr/ B. filkkerf w m om m 1 ,5 W i R ww o a? T .5 T B110. ham fly KRM B METHUD F SlZlNG NYLON TEXTILE MATE- RIALS WITH CQAL ACID CGMPOUNDS AND RESULTING ARTICLE Herbert B. Rickcrt, Keith B. liozer, and Robert S. Montgomery, Midland, and Marshall W. Duke, Bay City, Mich, assignors to The Dow Chemical Company, Midland, Mich, a corporation of Delaware Application July 3t), 1956, Serial No. 601,023

16 Claims. (Cl. 117--138.8)

This invention relates to the finishing of nylon yarns, threads, cords and the like filamentary structures and textile materials in order to facilitate their construction into cloth and fabric. The invention has particular reference to the sizing of nylon warp ends for subsequent weaving operations. It also relates to the finished nylon yarns and the like that are obtainable through its practice.

It would be an advantage to provide an effective and relatively inexpensive means for finishing textile yarns and the like that are comprised of essentially linear polyamide fibers and filaments, which frequently are generically characterized and referred to as nylon fibers, in order to facilitate their construction into cloth and fabric. Such a finish would be especially desirable if it could adequately protect the yarn during the course of its construction and conversion into cloth and fabric without exerting any adverse effect upon its physical or chemical constitution. Its utility would be replete and its desirability greatly enhanced if it were capable of temporary or fugitive application and did not require or involve the utilization of unusual or extraordinary scouring techniques to achieve its complete removal from the nylon yarn or fabric constructed therefrom. It would be particularly advantageous to provide such means to size nylon warp ends for subsequent weaving operations. Nylon yarn finished accordingly would be a most propitious commodity. The achievement of these desiderata and associated benefits is, therefore, among the principal objectives and purposes of the present invention.

To the realization of these and related ends, nylon yarn may advantageously be finished for its construction into cloth and fabric by the application thereto or do position thereon of a plastified film of mixed aromatic acid compounds such as may be obtained from the oxidation of coal which, for convenience, are hereinafter referred to as coal acid compounds. The coal acid compounds may either be the free coal acids, the watersoluble salts, particularly the alkali metal and ammonium salts, of the coal acids, or mixtures thereof. Beneficially, the finishing film of the coal acid compounds may be plastified by a solvent material for the coal acid com pounds that are selected from the described group and the finish application may be accomplished with a solo tion of the coal acid compounds in such solvent material. Preferably, the film is plastified with water and the coal acid compounds are applied in an aqueous solution in order to finish the nylon yarn. It is usually desirable to utilize the free coal acids for finishing nylon yarn, although in many instances and for many purposes, particularly where a less acidic finish may be attractive, the water-soluble coal acid salts may be used suitably. Advantangeously, warp ends of nylon yarn may be sized, preparatory to weaving, by application of an aqueous solution or mixture of the free coal acids or their watersoluble salts or mixtures of the free acids and their salts to the yarn by means of conventional slashing techniques.

.lflylonyarn that is finished or sized in accordance with.

, mechanical yarn handling apparatus.

the present invention with a plastified coal acid film, which, as indicated, may be comprised of either the free coal acids, their water-soluble salts or mixtures thereof, is adequately lubricated to minimize friction and has excellent resistance to abrasion upon passage through This facilitates its being woven or knit into cloth and fabric without injury or operational dificulty. In addition, the yarn is not harmfully or objectionably influenced by either discoloration or diminishment of physical properties due to the presence of the coal acid sizing finish. Besides this, a coal acid finish, comprised of either the free acids or their salts, is not injurious or significantly corrosive to the guides and other yarn contacting surfaces and elements in conventional yarn handling and cloth or fabric manufacturing equipment. Furthermore, nylon yarn that is provided with a coal acid finish may be scoured to a clean and finish-free condition by conventional techniques using the ordinarily employed detergent baths. The nylon yarn that is finished according to the invention is at least commensurate and may frequently be superior in these and other particulars to yarns finished or sized with conventional materials, such as polyacrylic acid and the like. A specimen of nylon yarn finished in accordance with the present invention is schematically represented in Figure 1 of the accompanying drawing.

Any solvent substance for the coal acid. compounds that is inert to nylon may be employed for the applicating solution and to plastify the finishing substance. It is, as indicated, usually most beneficial and preferred to utilize water for such purpose. However, in many cases, other solvent substances, particularly polar solvents, may be suitable, including glycerine, glycols, pol yglycols and the like, especially those having relatively high boiling characteristics. Aqueous mixtures of many polar solvents, such as water-glycol combinations, may also be found satisfactory for dissolving and plastifying the coal acid compounds.

Aqueous solutions of coal acids that contain between about 0.5 and 30 percent by weight of the coal acid com pounds, based on the weight of the solution, may generally be employed with benefit to finish nylon yarn for converhibit these desirable properties.

and 8 percent by weight of the coal acid compounds.

A sufiicient quantity of the solvent should be retained in the plastified coal acid film that envelopes the yarn as a finish to permit it to be soft, adequately flexible or' pliable and sufficiently lubricatory to achieve the desired function. The film should be sufiiciently plastified to allow suitable permeation of the yarn, especially when multiple filament yarns are involved, while remaining in a substantially continuous film phase on the surface of the yarn. It should alsobe capable of substantially regain- 1 ing its essential continuity on the surface after having been temporarily broken by such deformations of the yarn as bending or flaring of multiple filament yarns as may occur'in handling. Generally, a plastified coal acid film that contains between about 0.5 and 10.0 percent by' weight of water, based on the weight of the film, will ex- A water content in an aqueous plastified coal acid film that is in the desired range may usually be simply maintained by keeping the finishing film in equilibrium with air at a relatively greater than usually normal relative humidity, as is oridinarily effected fduring conventional cloth and fabric manufacturing op- .brium conditions through air drying. In some cases, how

erations. Such a water content, or equivalent concentrations of other solvents, may usually be achieved in the film after application of the coal acid solution by permitting the applied solution to approach or achieve equili- Patented Mar. 11, 1953 ever, it may be beneficial to employ heat at elevated temperatures in order to more quickly achieve the desired degree of plastification in the film after application of the solution. As is apparent, the actual water content of aqueous plastified coal acid films is generally dependent on the relative humidity of the atmosphere to which the finish films are exposed.

The nylon yarn may be finished so as to pick up or retain any desired quantity of the plastified coal acid film as a finish. For purposes of most fabric construction, there is usually little benefit to be achieved when a finish pick up greater than about 20 percent by weight, based on the weight of the yarn, is exceeded. Advantageously, the pick up may be between about 0.5 and percent by Weight. Often-times an amount of the plastified coal acid film on'the yarn that is in the neighborhood of 3 percent by weight may be found suitable, especially for purposes of finishing continuous filament yarns. When yarns that have been mechanically spun from staple lengths are being finished, it may sometimes be advantageous to apply comparitively greater quantities of the coal acid film than may be best suited for filament yarns. In addition, especially when spun yarns are being finished, it may also be beneficial to employ thickening agents in the applicating solution of the coal acids in order to facilitate achievement of the desired finish pick up on the yarn.

The finish application may be accomplished readily by immersing the yarn in the aqueous solution of coal acid compounds until the desired quantity of the coal acid compounds that are to remain in the plastified finishing film has been assimilated by the yarn. The usual type of operation that is involved in conventional slashing procedures using ordinary slashing or sizing mechanisms may be employed with expedience for such purposes. If desired, however, the aqueous or other solution of the coal acid compounds may be applied to the nylon yarn according to other known procedures for the application of textile finishes. Thus, as will be apparent to those skilled in the art, roller or wick finish applicators and liquid jet or spray devices and techniques may also be employed for application of the coal acid solution. As mentioned, air or other types of drying, as with the assistance of heated ovens or their equivalent, such as heat lamps, after application of the solution is usually sufficient for formation of the desired film finish. Any nylon yarn in twisted or untwisted condition that consists of multiple or individual continuous filament lengths or is fabricated by being spun from staple lengths may advantageously be finished according to the invention.

The mixed aromatic coal acid compounds that are employed for finishing nylon yarns in the practice of the invention may be identical with or similar to those which may be obtained by the oxidation with gaseous oxygen, which may be contained in the air, of an aqueous alkaline slurry of a finely divided carbonaceous material selected fromv the group consisting of coal and coke that has been obtained by the carbonization of coal at temperatures beneath about 700 C. Coal acid compounds that have been obtained by the nitric acid oxidation of suitable carbonaceous materials are also generally satisfactory. Such coals that are of the varieties known as anthracite, bituminous and lignite and other low grade coals are generally suitable for production of coal acids. Satisfactory cokes are those produced according to conventional techniques from coal at a temperature beneath about 700 C. The utilization of higher coking temperatures frequently causes the cokes that are obtained to be graphitic and rendered unsuitable for conversion to coal acid compounds in satisfactory yields.

The preparation of coal acid compounds from coal may, by way of illustration, involve mixing a ground bituminous coal with a caustic alkali, such as sodium hydroxide, and water, using an excess of the caustic with respect to the amount that is contemplated as being required for neutralizing the coal acidcompounds that are formed. Generally, an apparatus is employed that is constructed from a corrosion-resisting material of con struction and that is adapted for operation under pressure. The apparatus is also equipped with an efiicient mixing or agitating mechanism and with suitable heat-exchanging means. The weight ratio of the charged ingredients may, for example, be in the proportion of about three parts by weight of the coal to nine parts by weight of the caustic alkali to onehundred-twenty-five parts by weight of water. Oxygen is bubbled through the agitated charged ingredients while they are maintained at a temperature between about 200 and 300 C. and under a pressure of from about 500 to 1200 pounds per square inch. The exothermic reaction is continued until substantially all of the carbonaceous ingredients of the coal have gone into solution. This usually requires a period of time between about two and three hours. In the oxidation reaction that occurs, about half of the carbon in the coal is converted to organic acid compounds while the remainer is oxidized to carbon dioxide. Upon termination of the reaction and cooling of the reaction mass, the coal ash is filtered out of the alkali-neutralized coal acid solution that is obtained.

The free coal acids may then be isolated by acidifying.

such salts as sodium sulfate, which is obtained in the acidified free coal acid solution. Evaporation and drying techniques may be employed for subsequently isolating the free coal acids. The coal acids may thus be prepared as solid materials that are often pulverized for subsequent handling in a powder form.

The free coal acid product is a hygroscopic, usually yellowish, essentially water soluble material. Its watersoluble salts usually have similar characteristics. The free coal acid product is believed to be substantially comprised of various aromatic polycarboxylic acids. The average molecular weight of the coal acids that are ordinarily obtained is frequently in the neighborhood of 250. Their average equivalent weight is generally about 80. They ordinarily appear to have an average of from two and one-half to five carboxylic groups per molecule With an apparent average of about three to four being common. While their exact chemical nature and constitution may be somewhat conjectural, they evidently contain considerable quantities of triand tetra-carboxylic benzene acids as well as aromatic acids having more complex nuclei. Frequently, for example, the greatly preponderant proportion of aromatic nuclei obtained in coal acids prepared in the described fashion have been found to consist of methylnaphthalene, benzene, biphenyl, naphthalene, phenanthrene, alkyl benzene, benzophenone and toluene nuclei.

The employment of either the free coal acids, or their water-soluble salts, or mixtures thereof, for finishing nylon yarn depends to a great extent, as has been mentioned, on the degree of acidity that is desired in the finish. It is frequently more beneficial and may often be preferred, as indicated, to employ the free coal acids, which generally have a pH near 1, for this purpose. Less acidic coal acid finishes may be provided by utilization of the salts or various mixtures of the salts (including partial or acid coal acid salts) with the free coal acid product.

By way of further illustration, the efficacy of a coal acid finish on nylon multiple filament yarn, fabricated from the type of polyamide fiber-forming composition that is known and oftentimes referred to as nylon 66, was determined in a series of tests in which a denier, 34 filament twisted yarn having about 7.0 turns per inch was employed. A mixed aromatic free coal acid product was utilized that had been prepared by the alkaline oxidation of coal. It had an average molecular weight of about 270, an apparent equivalent weight of about 82 and, upon analysis, was found to contain about 54.4 percent by weight of combined carbon and about 3.0 percent by weight of combined hydrogen. The coal acid finishwas applied on the yarn by conventional slashing techniques using an aqueous solution of the coal acids that contained about 6 percent by weight of dissolved solids. The resulting plastified coal acid finish film was, with respect to its water content, in substantial equilibrium with air at a temperature of about 70 F. that had a relative humidity of about 65 percent. For purposes of comparison, the coal acid finished nylon yarn was tested along with yarn that was finished with a commercially available polyacrylic acid size for nylon which was employed in a conventional manner and applied by means of a slasher.

Several samples of both the coal acid finished and polyacrylic acid finished yarn, containing varied amounts of finish, were subjected to abrasion tests in which the yarn was run to a fray point at which the component individual filaments in the yarn remained flared out or spread apart when the yarn was not under tension. The test consisted of subjecting a plurality of taut ends of the finished yarn to the reciprocal abrading action of a pair of oscillating knife edges that were opposed to one another and in contact, in about perpendicular relative disopsition, with both sides of the yarn. The tests were conducted on a modified version of an apparatus that is known as a Duplan Cohesion Tester (for rayon and raw silk) which is manufactured by Geier & Bluhm, Inc. of Troy, New York and were performed in a generally analogous manner to the manufacturers recommended procedure. The number of oscillations or cycles required to cause failure of the yarn size and fraying of the yarn were observed in each of the tests. The results of the tests are graphically illustrated in Figure 2 of the accompanying drawing in which the fray point, as expressed in the number of cycles required for its accomplishment, is plotted against the quantity of finish on the yarn, expressed in percent by weight based on the weight of the yarn. The coal acid finished yarn is represented by a solid line in the graph while the yarn finished with the polyacrylic acid is represented by the dotted line. As is apparent, the coal acid finish was at least as effective in protecting the yarn from abrasion as was the conventional polyacrylic acid finish.

Several other samples of the same yarn, some of which contained one or the other of the finishes, were tested seven days after application of the finish in order to determine whether any excessively adverse effect on the physical propertiesof the yarn could be noted. The results are given in the following tabulation in which the original properties of the unfinished yarn are also included for comparativepurposes:

From the foregoing it is apparent that the coal acid finish did not have a degradative effect upon the nylon yarn, even when it was permitted to remain on the yarn for considerable periods.

Various scouring tests were performed on the finished nylon yarns. In one of the tests, a skein of yarn that had been sized with about 4.25 percent by weight of the water plastified coal acid film was washed with water for about fifteen minutes at a temperature between about 100 and 120 F. After the plain water scour the washed yarn was dried and analyzed for residual acid. None could be found, indicating complete and ready removal of the coal acid finish. In another of the tests, similar yarn samples that had coal acid finish applications of about 1 percent by weight were examined colorimetrically for traces of finish after having been washed at a temperature of about 150 F. for several minutes in a 0.25 percent by weight aqueous solution of Triton X- 100, an alkyl aryl polyether alcohol type of detergent that is available from Rohm & H-ass Company, and subsequently rinsed for ten minutes in warm water and dried. The samples were compared with a similarly scoured sample of unfinished yarn and also with one that had been finished with about 1 percent by weight of polyacrylic acid. The colorimetric examination consisted of wrapping the scoured yarn samples on small white plastic chips and analyzing them with a Model No. 75 Hunter color and color-difference meter supplied by the Henry A. Gardner Laboratory, Inc., of Bethesda, Maryland. This instrument photoelectrically measures the amount of reflectance (R and color (a+b) that is obtainable from the yarn samples. The reflectance value is a measure of the amount of light reflected from the yarn samples in comparison to that reflected from a standard white tile. The color value indicates the shade deviation of the sample from white. Negative a values are indicative of the presence of a blue-green color in the sample and positive b values are indicative of the relative degree of yellow that is present. The results that were obtained are included in the following table, which also includes the numerical b value that was obtained from the standard white tile:

Sample Size Employed Rd a 11" Standard White Til 77.0 +1.8 one 52. 8 3. 0 +3.0 Polyacryllc A0 54. 9 -2. 7 +3. 8 Coal Acids 52. 6 -3. 0 +3. 1 o 53. 3 3. 0 +3. 2

As is evident, the scouring with Triton X-ltlO served to completely remove the coal acids from the yarn. Had they remained after scouring, the )5 value of the color tested coal acid finished samples J and K would have been significantly increased due to the inherent characteristic yellow color of the coal acids.

In addition, other samples of 210 denier, 34 filament nylon yarn that had been sized from a 6 percent by weight aqueous solution of free coal acids to obtain about 3.4 percent by weight of the finishing film on the yarn were employed for both the warp and filling to weave excellent 60 x 66 square woven fabrics without operational difiiculties that might arise if the finish were inadequate for the purpose. The application of the coal acid finish and the subsequent weaving operation were performed at a temperature of about 70 F. with a relative humidity of about 55 percent. The woven coal acid finished fabric was at least as good as a similar fabric woven identically from. like yarn that had been sized with a 5 percent by weight aqueous solution of polyacrylic acid to deposit about 3.3 percent by weight of the polyacrylic acid finish on the yarn.

Excellent results similar to the foregoing may. also be obtained when coal acid finishes, including those comprised of water-soluble coal acid salts, such as sodium or ammonium salts, or mixtures thereof with free coal acids are applied on spun yarns, or when nylon yarns, either filament or spun, are sized or finished with coal acid compounds for subsequent knitting operations. In addition, the coal acid compounds may also be employed with benefit for finishing nylon yarns in accordance with the present invention when they are employed in combination with other finishes or sizing materials for nylon, including polyacrylic acid.

What is claimed is:

1. Method for finishing nylon yarn to facilitate its construction into cloth and fabric which comprises dcpositing on the surface of the yarn up to about 20 percent by weight, based on the weight plastified 'film ofcoal acid compounds selected from the group consisting of free coal acids, water-solublesalts of free coal acids and mixtures thereof, said coal acids being the water-soluble mixed aromatic polyc-arboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids have an average molecular weight of about 250, an average equiv alent weight of about 80, and contain an average of from about 2.5 to carboxylic groups per aromatic nuclei in their molecule.

2. Method for finishing nylon yarn to facilitate its construction into cloth and fabric which comprises applying to the yarn a solution of coal acid compounds selected from the group consisting of free coal acids, water-soluble salts of free coal acids and mixtures thereof and forming therefrom up to about 20 percent by weight, based on the weight of the yarn, of a plastified coal acid film on the surface of the yarn, said coal acids being the watersoluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids have an average molecular weight of about 250, an average equivalent weight of about 80, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nuclei in their molecule.

3. Method for finishing nylon yarn to facilitate its construction into cloth and fabric which comprises applying to the yarn an aqueous solution of coal acid compounds selected from the group consisting of free coal acids, water-soluble salts of free coal acids and mixtures thereof and forming therefrom up to about 20 percent by weight, based on the weight of the yarn, of a water plastified coal acid film on the surface of the yarn, said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and he like carbonaceous materials, which acids have an average molecular weight of about 250, an average equivalent weight of about 80, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nuclei in their molecule. a

4. The method of claim 3, wherein the aqueous applicating solution of the coal acid compounds contains be tween about 0.5 and 30 percent by weight of the coal acid compounds, based on the weight of the solution.

5. The method of claim 3, wherein the aqueous applicating solution of the coal acid compounds contains between-about 2 and 8 percent by weight of the coal acid compounds, based on the weight of the solution.

6. The method of claim 3, and including the intermediate step of drying the applied aqueous solution of coal acids to about moisture equilibrium with the surrounding atmosphere to form the plastified film thereof on the surface of the yarn.

7. The method of claim 3 wherein the coal acid compounds are the free coal acids.

8. The method of claim 3 wherein the nylon yarn is a multiple filament yarn.

9. Nylon yarn provided with up to about 20 percent by weight, based on the weight of the yarn, of a finish comprised of a plastified film of coal acid compounds of the yarn, of a V 7 selected from the group consisting of free coal acids, water-soluble salts of free coal acids, and mixtures thereof, said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids have an average molecular weight of about 250, an average equivalent weight of about 80, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nuclei in their molecule.

10. Nylon yarn provided with up to about 20 percent by weight, based on the weight of the yarn, of a finish comprised of a water plastified film of coal acid compounds selected from the group consisting of free coal acids, water-soluble salts of free coal acids and mixtures thereof, said coal acids being the'water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids have an average molecular weight of about 250, an average equivalent weight of about '80, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nuclei in their molecule.

11. Nylon yarn finished in accordance with claim '10 with between about 0.5 and 10 percent by weight of the water plastified coal acid film, based on the weight of the yarn, said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products ofthe oxidation of coal and the like carbonaceous materials, which acids have an average molecular weight of about v250, an average equivalent weight of about 80, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nuclei in their molecule.

12. Nylon yarn finished in accordance with claim 10 wherein the water plastified coal acid film is substantially in moisture equilibrium with the surrounding atmosphere.

13. Multiple filament nylon yarn finished according to claim 9.

14. Sized warp ends of nylon yarn in accordance with claim 9.

15. Nylon yarn finished with up to about 20 percent by weight, based on the weightof the yarn, of a water plastified film of free coal acids, said coal acids being the water-soluble mixed aromatic polycarboxylic acids that are the products of the oxidation of coal and the like carbonaceous materials, which acids have an average molecular weight of about 250, an average equivalent weight of about 80, and contain an average of from about 2.5 to 5 carboxylic groups per aromatic nuclei in their molecule.

16. The method of claim 3, wherein between about 0.5 and 10 percent by weight of said water plastified coal acid film is formed on the surface of said yarn.

References Cited in the file of this patent UNITED STATES PATENTS 2,324,601 Spanagel July 20, 1943 2,785,198 Grosskinsky et a1. May 12,1957

FOREIGN PATENTS 615,185 Great Britain Ian. 3, 1949. 

1. METHOD FOR FINISHING NYLON YARN TO FACILITATE ITS CONSTRUCTION INTO CLOTH AND FABRIC WHICH COMPRISES DEPOSITING ON THE SURFACE OF THE YARN UP TO ABOUT 20 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE YARN, OF A PLASTIFIED FILM OF COAL ACID COMPOUNDS SELECTED FROMTHE GROUP CONSISTING OF FREE COAL ACIDS, WATER-SOLUBLE SALTS OF FREE COAL ACIDS AND MIXTURES THEREOF, SAID COAL ACIDS BEING THE WATE-SOLUBLE MIXED AROMATIC POLYCARBOXYLIC ACIDS THAT ARE THE PRODUCTS OF THE OXIDATION OF COAL AND THE LIKE CARBONACEOUS MATERIALS, WHICH ACIDS HAVE AN AVERAGE MOLECULAR WEIGHT OF ABOUT 250, AN AVERAGE EQUIVALENT WEIGHT OF ABOUT 80, AND CONTAIN AN AVERAGE OF FROM ABOUT 2.5 TO 5 CARBOXYLIC GROUPS PER AROMATIC NUCLEI IN THEIR MOLECULE. 